1992 Volume 37 Issue 2 Pages 135-143
This study examined the difference in the force and EMG characteristics for the limb muscles with respect to growth-development and aging. Ten boys (age: 10.6 ± 1.1 yrs.), 8 adult men (25.3 ± 3.2 yrs.) and 7 elderly men (67.6 ± 2.4 yrs.) served as subjects for the study. The subjects were asked to perform isometric flexion and extention for elbow and knee at each force level of 25, 50 and 75% of their maximum voluntary contractions (MVC). Surface EMGs were recorded from the biseps brachii, triceps brachii, biceps femoris and rectus femoris muscles,respectively. Integrated EMG (IEMG) and mean power frequency (MPF) values were computed from the recorded EMGs at each of the three different force levels. Results were as follows: 1) IEMG values of the extensors (triceps brachii and rectus femoris muscles) for the adult group was significantly smaller than those of the boy and elderly groups at all force levels. 2) MPFs in both extensors and flexsors for the adult group were significantly larger than those for the boy and elderly groups at 75% and 100% MVC force levels. It was concluded that there was an aged-related difference in the force and EMG responces obtained from the limb muscles. This difference may be due to the effects of a different level of fast twitch fiber activation in force production.
